The present invention relates generally to physical exercising devices and, more particularly, to an adjustable resistance exercising device for use by athletes in performing isometric, isotonic, and isokinetic exercises, either independently or in combination.
Professional and amateur athletes frequently perform various exercises in an effort to increase their physical strength and endurance or to maintain a desired level of conditioning. Exercising devices such as bar bells, universal sets, nautilus equipment, and the like have been used by these athletes as an aid in building strength. However, such exercising devices are costly, require a great deal of permanent space, and are not easily transferred from one space to another space. Moreover, these devices are limited in that only one particular exercise can normally be performed at a time. Weights must be changed or equipment adjusted before the next exercise can be executed.
Less expensive exercise devices have been developed which rely on friction between a rope which the user pulls on and a shaft or the like around which the rope is wound. The friction or resistance developed by devices of this character is said to be "accommodating"--that is, at any given time through any given contraction the amount of resistance provided can be controlled by the individual operating the exerciser. Hence, various types of exercises can be performed with such a device.
Despite the lower cost of conventional friction-pulling type exercisers, they do have certain drawbacks. For example, some have multiple components, thereby increasing manufacturing costs and decreasing reliability. Others, such as those illustrated in U.S. Pat. Nos. 3,197,204, 3,411,766, and 3,717,339, carry a rope wrapped around a shaft which is enclosed by a housing, thereby making it somewhat difficult to vary the number of turns the rope takes around the shaft.
Other friction type exercising devices, such as those shown in U.S. Pat. Nos. 3,472,510, 3,510,132, and 3,656,745, do not carry the rope without a housing, but provide one or more shafts which form part of a closed structure. To change the number of turns around the shafts, the rope must be threaded through the enclosed structure, thereby making it somewhat difficult to quickly vary the number of turns on the shafts to change the resistance provided by the device. It is also difficult to obtain a selected number of turns on one of the shafts and a different number of turns on the other shaft without carefully threading the rope around the shafts.
Still another problem occurs with devices which operate by wrapping two free ends of a rope around the same shaft. With such an arrangement, the wrappings around the shaft may overlap and cause the rope to lock when tension is applied to it.
Accordingly, it is an object of the invention to provide an improved, adjustable resistance exercising device which overcomes the above-mentioned drawbacks of conventional exercisers.
It is a more specific object of the invention to provide such an exercising device for use with a rope wherein the number of rope turns around one or more shafts may be easily and quickly changed.
It is another object of the invention to provide such an exercising device which is relatively inexpensive to manufacture and which may be used for a nonstop series of isometric, isotonic, and isokinetic exercises.